HP 9121 9122 drives

[Tony Duell]

> 
> Anyone have docs & schematics for these? Dare I ask a service manual? I 

I have the ofifical service data for the 9121, it is useless. The only 
schematic is for the trivial linear PSU section.

One day I'll get round to tracing out schematics for the 9121. I can't do 
the 9122 as I don't have one. 

There are schematics for the double-sided drive (used in the 9122, at 
least the double-denisty version) on the HPCC CD-ROM, in the 9114A or 
Integral diagrams. 

What's the problem with your units? Most of these HP controllers follow 
much the same design with a 68B09 running the show, a little bit of RAM 
and EPROM, a Western Digital controller chip, 8291 GPIB chip, etc. 

Actually, most of the problems are mechanical and relate to dried-up 
grease on the eject mechanism. If you don't catch this in time, the disk 
holder is not latched correctly when you eject the disk and, on the 
double-sided units, the upper head is ripped off the gimbal spring. You 
have been warned!

-tony